HELSINKI, March 19 (Reuters) - A Helsinki court on Friday acquitted Finland's first woman prime minister of charges related to the leaking of secret documents on Iraq, a scandal that forced her to step down a year ago. The court cleared Anneli Jaatteenmaki of a charge of inciting or assisting the breach of official secrets, a scandal dubbed "Iraq-gate" by Finnish media that shocked a nation known abroad for its lack of corruption and straight-laced politics. But it said Martti Manninen, a former presidential aide who fed hundreds of pages of information to Jaatteenmaki by fax, should pay 3,600 euros...